5.4-stable review patch. If anyone has any objections, please let me know.
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From: Ilya Dryomov idryomov@gmail.com
commit 69c7b2fe4c9cc1d3b1186d1c5606627ecf0de883 upstream.
The way the delayed work is handled in ceph_monc_stop() is prone to races with mon_fault() and possibly also finish_hunting(). Both of these can requeue the delayed work which wouldn't be canceled by any of the following code in case that happens after cancel_delayed_work_sync() runs -- __close_session() doesn't mess with the delayed work in order to avoid interfering with the hunting interval logic. This part was missed in commit b5d91704f53e ("libceph: behave in mon_fault() if cur_mon < 0") and use-after-free can still ensue on monc and objects that hang off of it, with monc->auth and monc->monmap being particularly susceptible to quickly being reused.
To fix this:
- clear monc->cur_mon and monc->hunting as part of closing the session in ceph_monc_stop() - bail from delayed_work() if monc->cur_mon is cleared, similar to how it's done in mon_fault() and finish_hunting() (based on monc->hunting) - call cancel_delayed_work_sync() after the session is closed
Cc: stable@vger.kernel.org Link: https://tracker.ceph.com/issues/66857 Signed-off-by: Ilya Dryomov idryomov@gmail.com Reviewed-by: Xiubo Li xiubli@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/ceph/mon_client.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-)
--- a/net/ceph/mon_client.c +++ b/net/ceph/mon_client.c @@ -975,13 +975,19 @@ static void delayed_work(struct work_str struct ceph_mon_client *monc = container_of(work, struct ceph_mon_client, delayed_work.work);
- dout("monc delayed_work\n"); mutex_lock(&monc->mutex); + dout("%s mon%d\n", __func__, monc->cur_mon); + if (monc->cur_mon < 0) { + goto out; + } + if (monc->hunting) { dout("%s continuing hunt\n", __func__); reopen_session(monc); } else { int is_auth = ceph_auth_is_authenticated(monc->auth); + + dout("%s is_authed %d\n", __func__, is_auth); if (ceph_con_keepalive_expired(&monc->con, CEPH_MONC_PING_TIMEOUT)) { dout("monc keepalive timeout\n"); @@ -1006,6 +1012,8 @@ static void delayed_work(struct work_str } } __schedule_delayed(monc); + +out: mutex_unlock(&monc->mutex); }
@@ -1118,13 +1126,15 @@ EXPORT_SYMBOL(ceph_monc_init); void ceph_monc_stop(struct ceph_mon_client *monc) { dout("stop\n"); - cancel_delayed_work_sync(&monc->delayed_work);
mutex_lock(&monc->mutex); __close_session(monc); + monc->hunting = false; monc->cur_mon = -1; mutex_unlock(&monc->mutex);
+ cancel_delayed_work_sync(&monc->delayed_work); + /* * flush msgr queue before we destroy ourselves to ensure that: * - any work that references our embedded con is finished.